Aye Aye Mercaptan! T’aint Cork Taint! Part Four

Mar 30, 2014

Before I go into the next segment of this series, there’s a couple of things that I want to share.

Humans as a species are romantic. I know that I can be. Sitting out on the back patio on a moonlit night with the one you love while sharing a glass of a beautiful wine is something we can all relate to or dream about. Some people take it further. Adam Lee and his wife Diana of Siduri, for instance, decided to leave Texas with the dream of making wine in California. This was after one visit, mind you. They moved to California and have successfully realized their dream. How the heck does *that* happen?!? Anyway.

I have walked between rows of grapevines, felt the soil, marveled at budbreak, touched the leaves, and hefted the baby bunches of grapes. I’ve nibbled on juicy grapes still warm from the sun, punched down grapes after harvest, and tasted wine still in barrel. I’ve watched the bottles go through the wine filler while the precious fluid filled each bottle and the corks and capsules securely secured. You’d think that having all of those beautiful experiences among the stunning scenery and environment of wine country would make me long to be a winemaker.

And you would be wrong. Oh so very, very wrong.

While I already knew that I didn’t want to be a winemaker, this research project has more or less cemented the deal.

Winemakers have a lot of things to deal with. They have potential disasters waiting for them at every turn. If it isn’t the weather, it’s the pests. Then to worry about the pests and how they will affect the budding vines. Hopefully there are budding vines. Let’s hope the bees, hummingbirds, and butterflies come around to pollinate. Let’s hope for the grapes. Let’s hope for grape growth. Let’s hope for veraison. Can we get the grapes in before the juice begins to oxidize? Oh no! It’s raining and we’re ready to pick the grapes! What’s that gray stuff on the grapes?!? Dammit! Can we get enough people to hire or help during harvest? Did the harvester break down? Can we get them crushed?…

You get the idea. It goes on and on. So no, I don’t want to be a winemaker. I love and appreciate winemakers and frankly, I’m amazed that wine is as cheap as it is. To all winemakers who are passionate about your craft – I salute you, admire you, and honor you. If I had a hat on, I’d take it off in respect. You will have zero winemaker competition from me. Just make sure that it’s there for me to drink…that’s all I’m askin’.

And now to the topic at hand.

While the one wine flaw that is blamed on natural cork is TCA, there are a couple of issues – at least – that are associated with screwcaps, synthetic, and any other closures.

Mercaptans

Mercaptans are a group of thiols that can be stinky. If you’ve ever smelled natural gas, you’ve smelled mercaptans. Mercaptans are added to the otherwise odorless gas in order to warn people of its presence.

Not all thiols are harmful or stinky, actually. Some thiols have express chemical makeups that give such items as coffee, grapefruit, and black currant their distinctive smells and similarly the same aromas in wine.

However, other mercaptans smell like garlic, cabbage, burnt rubber, burnt matches, and are directly linked with sulfuric compounds. These compounds can be trapped in wines under screwcap because they thrive in an airless environment. Because they can cause a wine to have rubbery and soapy characteristics, they can render a wine undrinkable.

The manufacturers of screwcap closures are trying to find ways to make these closures more breathable – as cork is – and they certainly have their work cut out for them. According to chemist Geoffrey Taylor of the UK, whose lab tests about 10000 wines a year, the problem of mercaptan contamination in wines is from 2 to 4%, approximately the same as the current “corked” wine percentage.

As I said, this isn’t meant to bash screwcaps, but it is meant to put them in the correct light. They are not panaceas, and it is possible to have a tainted wine under screwcap.

Reductive

What does that mean? When I first heard the term, I thought that it had something to do with cooking.

Wines that are reductive (or reduced – it really comes down to semantics) have a smell similar to rotten eggs or natural gas. The odor can be dissipated by swirling copper in the glass or by shaking the bottle, preferably with some sort of copper. If that doesn’t dissipate the odor, the wine is considered to be undrinkable. (“Hm. This wine seems to be reductive. Let’s add in some potentially toxic heavy metal and see how it works…”) As with mercaptans, this character is exaggerated in an oxygen-free environment which is found when a wine is bottled under screwcap or under synthetic closures.

Reductive winemaking is a style that’s growing in popularity. The winemaker does his or her best to keep oxygen contact with the must down to a minimal level. This avoids premature oxidation and, at least in theory, should help extend the life of ageable wines.